Yang talked to a third-generation shipping co-owner in Vicksburg, Miss. who said "It's getting near critical. "Without more rain, we're heading into uncharted territory."

The American Waterways Operators says the river sees $180 billion of goods travel its surface every year. Five-hundred million tons of goods, according to NBC, that includes 60 percent of U.S. grain, 22 percent of its oil and gas, and one-fifth the nation's coal. "It would take 60 trailer trucks to carry the cargo in just one barge, 144 18-wheeler tankers to carry the oil and gas in one petroleum barge," NBC reports.